package com.eatme.core.hash;

import java.util.TreeMap;

public class HashTable<K,V> {
    private TreeMap<K,V>[] hashtable;

    private int M;

    private int size;

    public HashTable(int M) {
        this.M =M;
        size = 0;
        hashtable = new TreeMap[M];
        for (int i = 0; i < M; i++)
            hashtable[i] = new TreeMap<>();
    }

    public HashTable() {
        this(97);
    }

    private int hash(K key) {
        return (key.hashCode() & 0x7fffffff) % M;
    }

    public int getSize() {
        return size;
    }

    public void add(K key,V value) {
        TreeMap<K,V> map = hashtable[hash(key)];
        if (map.containsKey(key))
            map.put(key,value);
        else {
            map.put(key, value);
            size++;
        }
    }

    public V remove(K key) {
        TreeMap<K,V> map = hashtable[hash(key)];
        V ret = null;
        if (map.containsKey(key)) {
            ret = map.remove(key);
            size--;
        }
        return ret;
    }

    public void set(K key,V value) {
        TreeMap<K,V> map =hashtable[hash(key)];
        if (!map.containsKey(key))
            throw new IllegalArgumentException(key + "doesn`t exist!");
        map.put(key,value);
    }

    public boolean contains(K key) {
        return hashtable[hash(key)].containsKey(key);
    }

    public V get(K key) {
        return hashtable[hash(key)].get(key);
    }
}
